The present invention relates to replacing an existing main with a replacement main having a nozzle and vanes.
Gas, water and sewage mains may need to be replaced when they develop leaks or for other reasons. Leaks may develop at joints as a result of leak paths appearing within the joints in the case of cast iron gas mains or as a result of cracks in the wall due to corrosion or mechanical damage in cast iron and other materials e.g. ductile iron and steel, cement, brickwork or plastics.
In the case where the main to be replaced is a branch main joined to a fluid-carrying spine main, present techniques of mains replacement necessitate an excavation being made at the junction between the branch main and the spine main to gain access thereto. This is frequently in the middle of a busy thoroughfare and the excavation may lead to disruption of both pedestrians and traffic.